12th grade physics explainer video target for NEET 2026 in indian medical entrance exam---**Question Stem:**
An elevator has a mass of 4000 kg. The supporting cable has a tension of 52000 N. It is initially at rest. How far will it move in 4 sec?
**Options:**
(a) 40 m
(b) 52 m
(c) 13 m
(d) 24 m
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Let's solve this elevator physics problem step by step. We have an elevator with mass 4000 kg, supported by a cable with tension 52000 N. The elevator starts from rest and we need to find how far it moves in 4 seconds. First, let's identify the forces acting on the elevator.
Now let's calculate the gravitational force acting on the elevator. The gravitational force equals mass times gravitational acceleration. Using the standard approximation of g equals 10 meters per second squared, we get F g equals 4000 kilograms times 10 meters per second squared, which equals 40000 Newtons acting downward.
Now we calculate the net force and acceleration. The net force equals tension minus gravitational force: 52000 minus 40000 equals 12000 Newtons upward. Using Newton's second law, acceleration equals net force divided by mass: 12000 divided by 4000 equals 3 meters per second squared upward.
Finally, we apply the kinematic equation for displacement. Since the elevator starts from rest, initial velocity is zero. Using s equals v naught t plus one half a t squared, we substitute: s equals zero times 4 plus one half times 3 times 4 squared. This gives us s equals zero plus one half times 3 times 16, which equals 24 meters. The answer is option d, 24 meters.
Let's summarize our complete solution. We calculated the gravitational force as 40000 Newtons downward, found the net upward force as 12000 Newtons, determined the acceleration as 3 meters per second squared, and applied the kinematic equation to get a displacement of 24 meters in 4 seconds. The correct answer is option d, 24 meters. This problem demonstrates key physics concepts including Newton's second law, force analysis, and kinematic equations for constant acceleration.